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Erectile Dysfunction

Erectile Dysfunction

Erectile Dysfunction or Impotence is defined as being when a man is not capable of producing an erection which is sufficiently hard to achieve penetration. This can be caused by a number of factors which are discussed below.

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How Erections Form

Before we go on to explain the causes of erectile dysfunction, it might be useful if we describe how an erection forms in the first place. Most body parts are moved through muscular responses; the penis is not a muscle so can only move through a process of pressurisation involving blood flow. The penis contains two cylindrical chambers called the corpus cavernosa which fill up with blood through a network of arteries when a sexual stimulation signal is sent from the brain. The blood drains away from the corpus cavernosa through a network of veins. When the penis is flaccid, the arteries are constricted so let in relatively little blood and the veins are dilated in order to let blood flow away without any obstruction. When a man is sexually aroused, the brain sends a signal down nerve fibres in the body, instructing the arteries in the penis to expand. As the arteries expand, blood flows into the corpus cavernosa and the veins constrict, trapping pressurised blood in the penis and causing the erection to form.

Reasons for Erectile Dysfunction

In order for a man to achieve an erection it is important that the nerves leading to the penis are intact and working properly. There must also be adequate blood circulation and there must be a sexual stimulation signal from the brain. If any of these three essential ingredients are compromised in any way, an erection will not occur or the quality of the erection will be impaired.

Around 5% of men who are 40 years old suffer from long term erectile dysfunction which requires treatment. When we study the over 65s, the percentage jumps up dramatically, with some estimates suggesting that around 25% of men in this age range experience long term erectile problems. Throughout life, many men will experience occasional erectile problems which can be caused by a number of factors, such as tiredness, alcohol consumption and drug abuse. Some people will also experience performance anxiety with a new partner.

Specific Causes of Erectile Dysfunction

Prolonged erectile dysfunction can be a marker for underlying problems so we always recommend that men get a check up with their GP to rule out any deep rooted problems. The problems could be physical or psychological or a combination of the two.

Physical causes of erectile dysfunction are usually the result of a disease or injury which has resulted in one or more of the three essential factors necessary for an erection (set out above) being interrupted or damaged.


Diabetes can cause nerve and arterial damage which can in turn make achieving an erection difficult in this group of men. It is difficult to say exactly what percentage of men with diabetes will suffer from erectile dysfunction but some estimates have put this figure at around 75%. This seems a little high to us but we do see a lot of patients who are suffering from diabetes also experiencing problems with their erectile function. In most cases, the prescribing of an oral PDE5 inhibitor medication will resolve the problem.

Vascular Disease

Vascular diseases are those which affect the arteries such as arteriosclerosis which can be caused by smoking, high blood pressure and high cholesterol. These diseases affect blood flow, which in turn, has an impact on the ability to achieve an erection. It is estimated that around 70% of all physical cases of erectile dysfunction or impotence are caused by vascular issues. Often the medications used to treat the vascular condition can have an impact on the ability to get an erection and this is discussed later.

Kidney Disease

Kidney disease can have an impact on our chemical make up, including hormones and nerve function. This can in turn affect our ability to achieve an erection.

Neurological Diseases

Any disease that interrupts the signals that the brain sends out can have an impact on erectile function. Such diseases include Parkinson’s, Alzheimer’s, stroke or multiple sclerosis.


Some operations can cause damage to some of the nerves and tissue near the penis such as surgeries for prostate cancer and bladder cancer. Sometimes the damage will be permanent but in some cases the issue will resolve itself after the healing process which can be up to 18 months. There is evidence to suggest that the use of erectile dysfunction medications during the healing process will make it less likely that they are required when the healing process is complete as the nerves and tissues will have been stimulated when a natural erection was not possible.

Hormonal Imbalance

The lack of certain hormone chemicals in the body can make it difficult for a man to be sexually stimulated. This is a rare reason for erectile dysfunction but can be caused by kidney disease, liver disease or a tumour of the pituitary gland. Certain treatments for prostate problems can also cause a hormone imbalance.

Leaking Veins

If the veins in the penis are damaged and leak, blood cannot be prevented from leaving the penis and an erection is therefore not able to be sustained. This type of damage can be caused by either injury or disease.

Benign Prostatic Hyperplasia

Enlarged prostates have also recently been linked to causing erectile dysfunction. If someone is suffering from this condition, it is likely that any erectile dysfunction will be accompanied by urinary symptoms (like urinary frequency, urgency, hesitancy, poor stream or dribbling after urinating).

Psychological Factors affecting Erectile Dysfunction

It is estimated that up to 20% of all cases of erectile dysfunction are caused by psychological factors. These can range from stress caused by work, financial or marital problems to depression. Some men who have suffered from an episode of erectile dysfunction in the past may suffer from performance anxiety, which can in itself lead to a problem achieving an erection.

Medications Affecting Erectile Function

It is a well established fact that some medications can cause erectile dysfunction. While the drug is treating some condition, it can affect hormones, blood circulation and the nervous system, thereby leading to erectile dysfunction in some men. The number of medications which can cause erectile dysfunction is too numerous to list them here. If you are taking medication and you suspect that it may be the culprit behind your erectile dysfunction, it is very important that you do not stop the treatment as this will have an impact on the underlying condition that your doctor is treating. Most of the medications which can cause erectile dysfunction are compatible with the types of drugs now commonly used to treat erectile dysfunction so a doctor will probably be happy to prescribe something to help you get over the erectile issues without abandoning any other essential treatment.


There are a number of erectile dysfunction treatments available including those of Viagra, Pfizer Sildenafil, Cialis and Levitra. If the underlying cause of a man’s erectile dysfunction is a psychological issue then it may be advisable for him to seek sexual counselling. It is very important that the correct treatment is prescribed by a qualified medical practitioner.

If you would like to have a free consultation with The Online Clinic about your erectile issues, please complete the free consultation form and one of our doctors will have a look at it and get back to you.

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Reviewed by: Dr Joyce Braaksma
GMC registration number: 4621289
Date: 10 March 2022
Next review: 11 March 2024
All UK registered doctors can have their registration checked on
The Medical Register at the GMC website.

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